#define _CRT_SECURE_NO_WARNINGS 1 
#include <stdio.h>

//求 1 + 2 + 3 +  + 100 = ?

long sum(int n)
{
	if (1 == n)
	{
		return 1;
	}
	else
	{
		return n + sum(n - 1);
	}
}

int main(void)
{
	printf("1 + 2 + 3 + ... + 100 = ?\n");
	printf("结果为:> %ld\n", sum(100));
	return 0;
}